1. Field of the Invention
The present invention relates in general to a liquid crystal display (LCD) device integrating driving circuit on an active-matrix substrate. In particular, the present invention relates to a liquid crystal display device with low parasitical capacitance from clock lines.
2. Description of the Related Art
Liquid crystal display (LCD) devices are a well-known form of flat panel display with advantages of low power consumption, lightweight, thin profile, and low driving voltage. Generally, in the LCD, a liquid crystal layer is sandwiched between two transparent substrates such as glass substrates, one of which is provided with switching devices, such as thin film transistors (TFTs). In the display area of the LCD, an array of pixel areas is defined by horizontally extending gate lines and vertically extending data lines. Each pixel area has a thin film transistor and a pixel electrode.
An active matrix liquid crystal display used for a liquid crystal display with large area and high resolution includes pixel driving TFTs to drive display pixels and driver circuit TFTs for applying signals to gate lines and data lines coupled to the pixel driving TFTs. In general, there are two types of driver circuit unit. The first one embodies the driver circuit unit as a separate integrated circuit to drive signal lines, and the integrated circuit attached to one end of the substrate of the liquid crystal panel. In the second type, the driver circuit unit is formed on an LC panel as one piece. In the second type, typically, complementary metal oxide semiconductor thin film transistors (CMOS TFTs) using polycrystalline silicon (p-Si) with a high electric field effect mobility have been used for the driver circuit. Because the driver circuit TFTs and the pixel driving TFTs may be fabricated at the same time, the fabrication cost can be reduced.
However, the liquid crystal display device integrating driving circuit on an active-matrix substrate has a disadvantage of significant parasitic capacitance in the driver circuit region.
In order to solve this problem, U.S. Pat. No. 6,177,916 discloses a liquid crystal display device having a counter substrate without extending to the driver circuit region, such that the circuit on the matrix substrate of the driver circuit region cannot induce parasitic capacitance with the common electrode on the counter substrate.
However, with flat display panels getting larger, if the area of the matrix substrate is larger than that of the counter substrate, when backend module process is performed, the stress exerted on the flat display panel easily concentrates on the matrix substrate but is not evenly distributed, and the probability of panel damage increases.